I have a small 1000 sq. ft. house with a basement in Southwestern Ohio. The basement has about an 8" diameter hole (covered by a flap) in it that a handyman said was for air circulation for the Gas Furnace that I have in the basement. Do I really need outside air from this hole to run the furnace? Also, if the hole does serve the furnace, is there a way I can work around it and get the air from somewhere else? It seems very wasteful to me to have an open hole in a basement during Ohio winters, and I would like to block the hole. Thanks,
If your house is fairly new with very tight construction and tyvek and your furnace vents through a chimney it is possible you could not draft when the dryer and motorised vents such as bath vent are on. If so test it, but it is most likely unessesary
If it is properly installed, it is not wasteful, but saving you money.
You want to bring in combustion air from the outside. You don't want to burn up the air you just paid to heat, then suck in more cold air through cracks around windows and doors and have to reheat it again.
If you look at how your furnace works, you may get a better understanding of this. There is a heat exchanger that has the flame on one side, the inside air circulating on the other side. The air feeds the flame, then is carried up the flue along with any exhaust gases, carbon monoxide, etc, all stuff you don't want to breath. Meantime, the heat exchange is sort of a hot metal box and the inside air passes over it, gets warmed, and goes throughout the house.
"MD" wrote in news:1155726295.689597.292150 @i3g2000cwc.googlegroups.com:
Absolutely required. This is air that serves as combustion air for the furnace -- drawing it from inside your house leaves you at serious risk of furnace fires, CO/CO2 poisoning, or even explosions.
The air has to come from the outside of your house. Think of it this way
-- all of that cold air drawn in through the pipe is immediately sent right back outside again (up the chimney). The cold air hasn't contributed to any cooling of your house.
Buy a higher efficiency furnace -- they still draw combustion air from outside, but they extract almost all of the waste heat going up the chimney.
You use words like "seems like" Unless you know for sure, it is speculation on your part. More information would help. It is not a question of running with "no problems", it is question of using outdoor air for combustion, not the heated indoor air. That combustion air must come from someplace, even if you don't see it. Perhaps a vent in the old house would have cut your heating bill by 20%.
Where is the hole in relation to the furnace? What is the area of the stack and heat exchanger intake? What is the air requirements for combustion air in cfm? What is the Btu input of the furnace? A possible improvement may be to duct the intake closer to the heater intake if the area around the heater is not sealed off. .
FWIW, the boiler in a warehouse building that I operate has a motorized damper to allow fresh air in. The opening is about 60" x 48". Yes, you want to wear a jacket in the boiler room when it is running, but the rest of the building is nice and warm, very efficiently.
Evidently, you don't understand the theory or you would not think you are wasting a substantial amount of heat with the furnace running. The purpose of the vent is to AVOID wasting the heated air, instead, using the outdoor air for combustion. .
Does your gas furnace have a chimney (or is it a high efficiency with intake/output with PVC). If you have a chimney, the air for combustion has to come from somewhere, hence maybe the simple flap idea. An enclosed furnace room with outside air into that would be better.
However ... up here with a tighly sealed house and high efficiency heating, the air in a house can get mighty stale in winter without some sort of air exchange arrangement. So it could be that simple flap arrangement is serving 2 purposes ... combustion air and fresh air into the house ... and maybe that's what the handyman meant by air circulation.
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